1. Field of the Invention
This invention relates to protective headwear of the type designed to protect the head of the wearer by deflecting, distributing, or absorbing forces which would otherwise cause injury, and in particular to protective headwear of the type which least includes a rigid outer layer, such as a helmet or hard hat, having attached thereto a super-thin lighting element in the form of an electro-luminescent (EL) or photo-luminescent (PL) strip or panel, for the purpose of increasing dark environment safety, as well as for advertising and promotional purposes. By "super-thin" is meant that the lighting element has a thickness of less than 10 mm, preferably less than 3 mm, and still more preferably on the order of one millimeter in thickness or less so as to be easily attached to any hard or soft curved surface.
2. Discussion of Related Art
The inclusion of lighting elements on protective headwear such as helmets or hard hats is known from a number of prior patents, and is also described in U.S. patent application Ser. No. 08/226,329, filed Apr. 12, 1994, now abandoned, and a continuation of the copending application, U.S. patent application Ser. No. 08/436,007, filed May 5, 1995.
The present invention provides improvements over each of the prior arrangements, either in terms of performance or safety. In many of the prior arrangements, accommodation for the lighting arrangement negates the protective effect of the headwear, and may in itself present a hazard. In others, the arrangement is simply too complicated or expensive for use in most protective headwear applications.
U.S. Pat. No. 4,231,079, for example, discloses an illumination arrangement for protective hat in which a plurality of LEDs are arranged in a single layer. However, the arrangement disclosed in this patent has the disadvantage that, in order to connect the LEDs to a power source located inside the hat, holes must be drilled into the hat, thereby compromising the integrity of the hat's construction, with potential weakening of the structure of the hat and therefore of the protection provided by the hat. In addition, the arrangement shown in this patent has a number of disadvantages common to all lighting arrangements involving LEDs, including a relatively narrow viewing angle, limited color choice, and relatively difficult assembly to the hat, particularly if area wide lighting is desired, such as might be the case if the lighting arrangement is used for advertising or promotional purposes. Still further, the LEDs, disclosed in this patent as being positioned in the hat and soldered to the electrical connections, present a hazard in themselves as they could possibly be pushed during a strong impact into the head of the wearer, which could cause a terrible brain injury.
Another example of illuminated protective headwear, in this case a motorcycle helmet, is disclosed in U.S. Pat. No. 4,901,210. Like the arrangement described in the Heminover patent, the arrangement described in this patent has the disadvantage that it requires drilling of holes into the helmet to provide a connection to a power source located inside the helmet, which could weaken the helmet structure, and in addition, the arrangement described in this patent utilizes a relatively bulky housing construction which is exposed to breakage during impacts against the helmet and therefore presents a potential injury hazard to the wearer, only partially mitigated by the fact that the illumination housing is placed at the rear of the helmet.
U.S. Pat. No. 5,111,366, on the other hand, discloses a soft cap having an area light which uses optical properties of a plastic panel to achieve a desired effect. As in the prior protective headwear arrangements, the use of LEDs described in this patent requires a complicated structure, costly assembly, and while the problem of narrow viewing angle is overcome by the optical panel, the LEDs provides only limited color choices.
Another prior disclosure of a lighting arrangement for headwear in general is found in U.S. Pat. No. 1,572,210. This patent also does not involve protective headwear, and the lighting arrangement described therein would in fact not be suitable for protective headwear because it involves placement of incandescent glass bulbs on a visor, and therefore a serious risk of injury to the face, head, and brain. In addition, the use of incandescent lighting has the disadvantage of requiring a relatively large power supply.
Similarly, U.S. Pat. No. 4,901,211 describes an illuminated visor structure using unspecified lighting means, but requiring a complicated housing structure which would be both impractical and hazardous to use in any type of headwear intended to serve a protective function.
On the other hand, U.S. Pat. No. 5,327,587 discloses an illuminated helmet which includes provision for an EL light strip mounted on an outside surface of the helmet, resulting in exposure of the light strip to damage from impacts and environmental influences.
Finally, British Patent Publication No. UK 0 166 534 describes an arrangement in which an EL light is housed within a transparent envelop which can be attached to a hat, but the EL light arrangement disclosed therein is impractical, particularly for use in protective headwear. Among the disadvantages of this arrangement is that the envelope would be very difficult to apply to a smooth surface such as a hard hat or helmet surface, and in addition the transparent envelop does not provide adequate protection for the EL material from ultra-violet radiation and from moisture.
As is apparent from the above description, the majority of prior art designs use incandescent bulbs or LEDs. In order to put even the smallest practical LEDs on a helmet, hard hat, or other protective headwear, the protective headwear must be provided with appropriate openings and/or indentations or the lighting elements will project from the surface of the hard hat (a minimum length for an LED is 10 mm, with a 3 mm diameter). Furthermore, because the maximum viewing angle of an LED is 45.degree., a large number of LEDs are required in order to obtain a large viewing angle. In addition, the electric wire connections between each LED require soldering at least two points, for the positive and negative connections, to the control circuit, necessitating additional labor and also a relatively large control circuit board, which means that the space required to mount an LED includes at least 10 mm of LED body length+1 mm thickness of printed circuit board+2 mm thickness for the soldering terminal, which totals 13 mm thickness for each LED. It is very difficult to mount such a fixture on the outside of the helmet, and the external fixture can, as noted above, itself present a hazard to the wearer because of the possibility that the lighting fixture will be pushed into the head of the wearer, as a result of which many countries have safety regulations prohibiting such installations on safety helmets or hard hats. The use of incandescent bulbs is clearly even more disadvantageous than the use of LEDs because they are more fragile, occupy a bigger volume, and use more power. Even designs which contemplate the use of EL strips or panels, encased in a transparent envelope, are inadequate for use in protective headwear, due to manufacturing or assembly difficulties and inadequate protection of the EL device itself from such environmental hazards as ultraviolet (UV) radiation and humidity.